1. Field of the Invention
The present invention relates to a recognition system for identification-card singularity on digital network communication between a master station and detail stations by means of using a master communication device attached to the master station, detail communication devices attached to the detail stations, respectively, and identification cards set in the detail communication devices, respectively.
2. Description of the Prior Art
It is most important on digital network communication to prevent the influence of noises and invaders. However, it is difficult to keep the communication secret by the coding technique based on conventional hard-wears such as magnetic cards and IC cards. The magnetic cards are very convenient and popular, however it is easy to make copies thereof or steal passwords. Therefore damages by unlawful using of credit cards, cash cards, prepaid cards, and so on are increasing year after year. The IC cards are superior to the magnetic cards in difficulty in counterfeiting of cards, however it is not enough to keep the communication secret thoroughly. Thus, conventional hard-wears have problems on keeping a communication security.
An object of the present invention is to provide an identification card useful as credit card, cash card, key, and others.
Another object of the present invention is to provide an identification card excellent in difficulty in counterfeiting and stealing of passwords.
Another object of the present invention is to provide a recognition system for identification-card singularity capable of recognizing the identification-card singularity in secret.
Another object of the present invention is to provide a recognition system for identification-card singularity capable of low electric power consumption.
Another object of the present invention is to provide a recognition system for identification-card singularity excellent in durability and manufacturing.
A still other object of the present invention is to provide a recognition system for identification-card singularity having a small size and a simple structure.
According to one aspect of the present invention there is provided a recognition system for identification-card singularity comprising a master communication device attached to a master computer, a detail communication device attached to a detail computer, and an identification card set in the detail communication device. The identification card consists a first piezoelectric substrate, an individual coded interdigital transducer (IDT), and a first electrode-group. The individual coded IDT consists of interdigital electrode pairs Pi (i=1, 2, . . . , n), of which two neighbors are at a distance L from each other, and has an individual coded pattern. The first electrode-group consists of an interdigital electrode I0 and an interdigital electrode Ii (i=1) at a distance iL (i=1) from the interdigital electrode I0. The detail communication device consists of a second piezoelectric substrate and transmitting- and receiving sections. The transmitting section is composed of a first bipolar-pulse generator, first and second coded IDTs, a second electrode-group, an envelope detecting device, and a monopolar-pulse generator. The first coded IDT consists of interdigital electrode pairs Pi (i=1, 2, . . . , n), of which two neighbors are at the distance L from each other, and has a first coded pattern. The second coded IDT has the same construction as the first coded IDT except for having a second coded pattern. The second electrode-group consists of an interdigital electrode A0 and an interdigital electrode Ai (i=1at the distance iL (i=1) from the interdigital electrode A0. The envelope detecting device is connected with the second electrode-group. The master communication device has the same construction as the detail communication device, and consists of a third piezoelectric substrate and transmitting- and receiving sections. The receiving section is composed of a third electrode-group, a second bipolar-pulse generator, an intermediary IDT, third and fourth coded IDTs, and a detecting device. The third electrode-group consists of a central interdigital electrode B0M, a left interdigital electrode B1M at a distance L0 from the central interdigital electrode B0M, and a right interdigital electrode BiM (i=1) at a distance L0+iL (i=1) from the central interdigital electrode B0M. The third coded IDT has the same construction as the first coded IDT except for having a third coded pattern. The fourth coded IDT has the same construction as the first coded IDT except for having a fourth coded pattern.
If the identification card is set in the detail communication device, a pulse generated at the first bipolar-pulse generator is applied to the individual coded IDT, so that an individual SAW corresponding to the individual coded pattern is excited on the first piezoelectric substrate. The individual SAW is detected as an individual coded burst-signal at the interdigital electrode I0, and after a time corresponding to the distance L, at the interdigital electrode I1 again. The individual coded burst-signals at the interdigital electrodes I0 and I1 form an individual double-coded burst-signal, which arrives at the monopolar-pulse generator via the envelope detecting device. Thus, an individual double-coded digital-signal is obtained at the monopolar-pulse generator, and is delivered into a digital network. On the other hand, when the individual double-coded digital-signal arrives at the master communication device, it is received at the left interdigital electrode Bxe2x88x921M and the right interdigital electrode B1M, respectively. In this time, first- and second SAWs are excited on the third piezoelectric substrate. The first SAW arrives at the central interdigital electrode B0M by a time corresponding to the distance L before the second SAW arrives at the central interdigital electrode B0M. As a result, the individual double-coded digital-signal is converted into an individual mono-coded burst-signal at the central interdigital electrode B0M. The individual mono-coded burst-signal is converted into an individual mono-coded digital-signal at the second bipolar-pulse generator. The individual mono-coded digital-signal is applied to the intermediary IDT. And then, a third SAW composed of an individual coded row of burst-wave groups is excited on the third piezoelectric substrate. When the burst-wave group correlates to the third- and fourth coded patterns, respectively, first- and second decoded pulses are detected at the third- and fourth coded IDTs, respectively. As a result, an output digital-signal equivalent to the individual coded pattern, is detected at the detecting device. Therefore, the identification-card singularity is recognized from the output digital-signal.
In addition, for further securing such a communication system, a double-coded request digital-signal asking for password is delivered from the transmitting section of the master communication device into the digital network toward the detail communication device just after recognition of the identification-card singularity. The double-coded request digital-signal asking for password is received at the receiving section of the detail communication device through the digital network. And then, a double-coded password digital-signal is delivered from the transmitting section of the detail communication device into the digital network. The double-coded password digital-signal is received at the receiving section of the master communication device through the digital network. Thus, the communication between the master communication device and the detail communication device starts.
According to another aspect of the present invention there are provided first-, second-, third-, and fourth coded IDTs consisting of at least three interdigital electrode pairs, respectively.
According to another aspect of the present invention there are provided third- and fourth coded IDTs having third- and fourth coded patterns in reverse to the first- and second coded patterns, respectively.
According to another aspect of the present invention there is provided an individual coded IDT constructed of multiple times four coded IDTs classified into at most two types that correspond to the first- and second coded IDTs, respectively.
According to another aspect of the present invention there is provided a bipolar-pulse generator in place of the monopolar-pulse generator.
According to another aspect of the present invention there is provided an individual coded IDT comprising at least two parts that are electrically separated and in uneven parallel with each other. The parts excite individual SAWs, respectively, on the first piezoelectric substrate when receiving the pulse from the first bipolar-pulse generator simultaneously. The interdigital electrode I0 detects individual coded burst-signals one by one when receiving the individual SAWs. The interdigital electrode I1 also detects the individual coded burst-signals one by one when receiving the individual SAWs. As a result, the individual coded burst-signals at the interdigital electrodes I0 and I1 form a mixed double-coded burst-signal corresponding to the individual double-coded burst-signal received at the envelope detecting device.
According to other aspect of the present invention there are provided an individual coded IDT comprising first- and second parts that are electrically separated and vertical from each other, and an identification card further comprising a fourth electrode-group that consists of an interdigital electrode J0 and an interdigital electrode Ji (i=1) at a distance iL (i=1) from the interdigital electrode J0. The first- and second parts excite first- and second individual SAWs, respectively, on the first piezoelectric substrate when receiving the pulse from the first bipolar-pulse generator simultaneously. The interdigital electrode J0 detects a first individual coded burst-signal corresponding to the first individual SAW. The interdigital electrode J1 detects the first individual coded burst-signal again. The interdigital electrode I0 detects a second individual coded burst-signal corresponding to the second individual SAW just after the interdigital electrode J0 detects the first individual coded burst-signal. The interdigital electrode I1 detects the second individual coded burst-signal just after the interdigital electrode J1 detects the first individual coded burst-signal. As a result, the first- and second individual coded burst-signals at the interdigital electrodes J0, J1, I0 and I1 form a mixed double-coded burst-signal corresponding to the individual double-coded burst-signal received at the envelope detecting device.
According to a further aspect of the present invention there are provided a first electrode-group, a second electrode-group, a third electrode-group, an identification card, a transmitting section, and a receiving section. The first electrode-group includes at least two interdigital electrodes Ii {i=1, 2, . . . , (nxe2x88x921)} at a distance iL {i=1, 2, . . . , (nxe2x88x921)}, respectively, from the interdigital electrode I0. The second electrode-group includes at least two interdigital electrodes Ai {i=1, 2, . . . , (nxe2x88x921)} at a distance iL {i=1, 2, . . . , (nxe2x88x921)}, respectively, from the interdigital electrode A0. The third electrode-group includes at least two right interdigital electrodes BiM {i=1, 2, . . . , (nxe2x88x921)} at a distance L0+iL {i=1, 2, . . . (nxe2x88x921)}, respectively, from the central interdigital electrode B0M. The identification card further comprises a first switch that connects the envelope detecting device with the interdigital electrodes Ii in turn. The transmitting section further comprises a second switch that connects the envelope detecting device with the interdigital electrodes Ai in turn. The receiving section further comprises a third switch that connects the digital network with the right interdigital electrode BiM in turn.